Curable epoxy resin composition, and fiber-reinforced composite material obtained using same

A resin composition for a fiber-reinforced composite material, comprising, as essential components:

• an epoxy resin (A);
• an acid anhydride-based curing agent (B);
• an imidazole-based curing accelerator (C);
• and
• a radical-polymerizable monomer (D) that is free of an acid group and that is liquid at 25° C. in addition to the epoxy resin (A), the acid anhydride-based curing agent (B), and the imidazole-based curing accelerator (C), wherein a blending amount of the radical-polymerizable monomer (D) is from 5 parts by mass to 25 parts by mass with respect to 100 parts by mass of a total amount of the component (A), the component (B), the component (C), and the component (D),
• the resin composition capable of being applied to or impregnated into reinforcing fibers in a wet lay-up molding method, a pultrusion molding method, or a filament winding molding method without using a solvent,
• wherein 50 mass % or more of the epoxy resin (A) comprises a phenol novolac-type epoxy resin containing a compound represented by the following general formula (1) and a compound represented by the following general formula (2),
• wherein, in gel permeation chromatography measurement, the phenol novolac-type epoxy resin contains a body corresponding to m=0 of the compound represented by the following general formula (1) at a ratio of 75% by area or more and a body corresponding to m=1 thereof at a ratio of 6% by area or less, and
• wherein the composition has a viscosity (25° C.) measured with an E-type viscometer in a range of from 50 mPa·s to 800 mPa·s, and the composition shows a viscosity increase ratio (25° C.) after a lapse of 6 hr of 200% or less:
• where m represents an integer of 0 or more, and represents from 0 to 5;
• where n represents an integer of 0 or more, and represents from 0 to 2.